- Ophelia Lovibond - Jessica Rattenbury
- Bradley James - Jack Roth
- Michael Pennington - Dr. Melville
- Neil Pearson - Dr. Stringer
- Nathaniel Parker - Philip Coleman
- Joanna Lumley - Esme Ford
- Julian Wadham - Tom Rattenbury
- Rachael Stirling - Zoë Kenneth
- Tom Riley - Philip Horton
- Richard Johnson - Augustus Mortmaigne
- Jenny Seagrove - Cecile Rattenbury
- Oliver Milburn - Charlie Newton
- Jack Gordon - James Coupland
- Guy Henry - Professor Pelham
- Michael Simkins - Manfred Canter
- Ian McNeice - Reverend King
- Haydn Gwynne - Sandra Walters
- Gerard Horan - DC Hooper
- Tom Mison - Dorian Crane
- David Ryall - Mr. Cooper
- Stella Gonet - Frances Woodville
- Hugh O'Conor - Father Jasper
- Jonathan Bailey - Titus Mortmaigne
- Trevor Byfield - Bone
- Taron Egerton - Liam Jay
- James Davies - Jarvis Patterson
- Shola Adewusi - Cleaner
- Renee Montemayor - Jacinta
- Lucy Griffiths - Madeleine Escher
- Lucy Speed - Louise Cornish
- Nina Sosanya - Lilian Hunter
- Tom Brooke - Brian Miller
- Finn Cole - Ollie Tedman
- Marty Cruikshank - Woman Interviewee
- Liz Crowther - Mrs. Leeming
- Bryan Dick - Phil Beaumont
- Daniel Sharman - Richard Scott
- Geoffrey Breton - Joe Myers
- Josephine Tewson - Hazel O'Brien
- Gabrielle Lloyd - Eileen Norman
- Eva Sayer - Anna Mallory
- Richard Lintern - Sefton Linn
- Sian Thomas - Ingrid Nielson
- Adrian Rawlins - Harry Bundrick
- Richard Dillane - Theodore Platt
- Anna Massey - Prof. Margaret Gold
- Anna Madeley - Anne Sadikov
- Emily Beecham - Nell Buckley
- Caroline O'Neill - Susan Chapman
- Philip Battley - Will McEwan
- Matthew Marsh - Henry McEwan
- Chiké Okonkwo - Jonjo Read
- Kate Miles - Nova Rose
- Bruce Mackinnon - Conan Jones
- Deborah Findlay - Lady Hugh
- Zoe Boyle - Hope Ransome
- Ben Aldridge - Daniel Rattenbury
- Camilla Arfwedson - Scarlett Mortmaigne
- Juliet Aubrey - Selina Mortmaigne
- Warren Clarke - Roger Temple
- Deborah Cornelius - Dr. Ella Ransome
- Sophie Ward - Isobel Crompton
- Robert Hardy - Sir Arnold Raeburn
- Diana Quick - Gwen Raeburn
- Annabelle Apsion - Babs Temple
- Andrew Hawley - Jez Haydock
- Bernard Lloyd - Ted Temple
- Christopher Bowen - Professor Andrew Crompton
- Zoe Telford - Freya Carlisle
- Kathryn O'Reilly - Poppy Toynton
- Juliet Stevenson - Diana Ellerby
- Hattie Morahan - Ruth Brooks
- Antonia Campbell-Hughes - Chloe Brooks
- Saskia Reeves - Alison McLennan
- Stephanie Street - Lakshmi Eyre
- Cherie Lunghi - Grace Orde
- Lucy Boynton - Zoe Suskin
- David Westhead - Leon Suskin
- Anna Chancellor - Judith Suskin
- Lorcan Cranitch - Liam Cullen
- Elize du Toit - Andrea De Ritter
- Leanne Rowe - Carly Cliff
- Oliver Johnstone - Vincent Vega
- Annabel Mullion - Thea Falconer
- James Fleet - Dr. Alex Falconer
- Nadine Lewington - Liv Nash
- Alex Jennings - Rev. Conor Hawes
- Matilda Ziegler - Helena Wright
- Richard Durden - John Gracey
- Celia Imrie - Michelle Marber
- Daisy May - Mia Wallace
- Julie Cox - Miranda Thornton
- Freddie Fox - Sebastian Dromgoole
- Roxanne McKee - Briony Keagan
- Josh O'Connor - Charlie Stephenson
- Toby Stephens - David Connelly
- Daniel Lapaine - Kit Renton
- Jo-Anne Stockham - Helen Mitchell
- Abigail Hardingham - Jessica Lake
- Georgia Taylor - Honey Addams
- Ciarán McMenamin - Nick Addams
- Lucy Cohu - Marion Hammond
- Con O'Neill - Dr. Bob Massey
- Leila Mimmack - Yasmin Randall
- Kemi-Bo Jacobs - WPC Julie Lockhart
- Kemi-Bo Jacobs - DC Lockhart
- Anna Wilson-Jones - Stanza Massey
- Harriet Madeley - Emily Robinson
- Richard Southgate - Will Pascoe
- David Soul - Paul Yelland
- David Calder - Andrew Lipton
- Pippa Bennett-Warner - Nina Clemens
- Jason Durr - DI Peterson
- Jake Curran - Adam Pettle
- Nancy Carroll - Anne Rand
- Patrick Baladi - Robert Fraser
- Rita Davies - Edna O'Brien
- Edwin Thomas - Reuben Beatty
- Catherine Steadman - Polly Beatty
- Beatie Edney - Justine Skinner
- Tuppence Middleton - Vicki Walmsley
- Neil Stuke - Professor Andrew Crane
- Dominic Mafham - Frank McLean
- Emily Joyce - Jane Grace
- Sanjeev Bhaskar - Kanan Dutta
- Lesley Vickerage - Katherine Dutta
- Simon Wilson - Dr. Matt Whitby
- Lia Williams - Emma Barnes
- Peter Davison - Peter Faulkner
- Camilla Power - Tara Faulkner
- Babou Ceesay - DC Alex Gray
- Alison Steadman - Rev. Martha Seager
- Miranda Raison - Stella Drew
- Edward Fox - Dr. Yardley
- Crystal Leaity - Rachel Cliff
- Andrew Paul - Ron Tibitt
- Kirsten Foster - PC Stapleton
- Stephen Churchett - Richard Seager
- Jane Slavin - Debbie Cliff
- Ariyon Bakare - Carl Drew
- Josh Bolt - Adam Tibitt
- Katrine De Candole - Davina Garland
- Naomi Scott - Sahira Desai
- Jaygann Ayeh - Nate
- Francesca Zoutewelle - Jess Tallison
- Aisling Bea - Hotel Receptionist
- Adam James - Ethan Croft
- Susannah Doyle - Jean Croft
- Ruth Gemmell - Robyn Strong
- Sally Bretton - Eve Rigby
- Ian Mercer - Lester Garvey
- Anna Koval - Diane Baxter
- Jamie Michie - Brian Kaye
- Alan Davies - Marcus Richards
- Timothy West - Donald Terry
- Jack Fox - Alfie Wilkinson
- Tabitha Wady - Ava Taylor
- Nicholas Farrell - Charles Milner
- Alastair Mackenzie - Sebastian Anderson
- Emma Cleasby - Jessica Neill
- Kazia Pelka - Susan Banks
- Helen Grace - Gwen Milner
- Paul Reynolds - Mr. Davies
- Tim Pigott-Smith - Jasper Hammond
- Nicholas Jones - Philip Hathaway
- Doreen Mantle - Joan
- Bobby Lockwood - Sam Langton
- Dan Reed
- Maurice Phillips
- Bille Eltringham
- Rachel Bennette
- Colin Dexter
- Alan Plater
- Chris Burt
- Damien Timmer
- Michele Buck
Daniel Lapaine interpreta a Kit Renton en la serie.
Adrian Rawlins hace el papel de Harry Bundrick.
Richard Lintern interpreta a Sefton Linn en la serie.
Ian McNeice hace el papel de Reverend King.
Warren Clarke interpreta a Roger Temple en la serie.
Jake Curran interpreta a Adam Pettle en la serie.
Kevin Whately interpreta a Detective Inspector Robert 'Robbie' Lewis en la serie.
Laurence Fox hace el papel de Detective Sergeant James Hathaway.
Clare Holman hace el papel de Dr. Laura Hobson.
Rebecca Front hace el papel de Chief Superintendent Jean Innocent.
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